I've also noticed this, I really hope it hasn't died the vocab lists there are great and I was planning to work my way through the JLPT3+2 vocab sections once trinity came online, I hope someone has a backup save of the site.
The other day I sent an email to Peter van der Woude of jlptstudy.com. He replied:
Peter wrote:
The computer that's hosting the site has had some catastrophic failure. I'm a bit surprised it's taking over a week to fix but I can only wait. It will come back eventually !
An update in case anyone didn't know that the site is back up. I've no idea how long it was down but it looks like an excellent resource for thoe pursuing JLPT. One day I hope to benefit from it, but in them meantime back to RTK1 for me . . . !